A North Korean man sits beside a pile of coal on the bank of the Yalu River in the North Korean town of Sinuiju in this December 16, 2006 file picture. (Photo by Adam Dean/Reuters)

A cargo boat (R) is seen on the bank of the Yalu River in Sinuiju, opposite the Chinese border city of Dandong, March 14, 2016. Picture taken from China's side of the Yalu. (Photo by Jacky Chen/Reuters)

Dancing parties of youth and students took place Monday across the country on the occasion of the 4th anniversary of supreme leader Kim Jong Un's assumption of the top posts of the party and the state, in this photo released by North Korea's Korean Central News Agency (KCNA) on April 11, 2016. (Photo by Reuters/KCNA)

Dancing parties of youth and students took place Monday across the country on the occasion of the 4th anniversary of supreme leader Kim Jong Un's assumption of the top posts of the party and the state, in this photo released by North Korea's Korean Central News Agency (KCNA) on April 11, 2016. (Photo by Reuters/KCNA)

North Korean push their bicycles along a road on Monday, February 22, 2016, in Kaesong, North Korea. In response to the North's recent long-range rocket launch, Seoul shut down a factory park in Kaesong jointly run by both Koreas and this has cost the impoverished North a rare source of legitimate hard currency. (Photo by Wong Maye-E/AP Photo)

Schoolchildren play music to entertain and inspire people on their way home from work Tuesday, March 29, 2016 in Pyongyang, North Korea. North Korea has called a 70-day loyalty drive areas of a major congress of the ruling party scheduled for early May and everyone from students to coal miners have been mobilized nationwide to demonstrate their devotion to the leadership. (Photo by Eric Talmadge/AP Photo)

On a moving pavement, men pass a photo of the Dear Leaders in Kumsusan Palace after visiting their bodies which lie, “lit de parade,” or in repose for viewing. Pyongyang is said to have 2.5 million inhabitants. Only the upper caste, known as the core class, is allowed to stay in the capital. In reality, no one outside North Korea knows the exact population. (Photo by Peter Hove Olesen)

A group of soldiers wait at a bus stop. It is estimated that North Korea has the fourth largest army in the world with 1.21 million soldiers. If the number is correct, it means one in 25 North Koreans is employed by the military. It is not allowed to photograph the military in North Korea. The photo was taken in hiding with a small camera under one of the few walks, we were allowed to make in the capital. (Photo by Peter Hove Olesen)

The Pyongyang Metro is an impressive display of marble, chandeliers, and mosaics – at least at the three stations we are allowed to see. According to North Korean defectors, it is always the same three metro stations which are shown to foreigners. (Photo by Peter Hove Olesen)

A young couple on the way to Kumsusan Palace. Kim Jong Il died in December, 2011. The North Korean news agency reported that an earthquake shook Mount Paeku where the Dear Leader was born while crying owls flew into the mausoleum. (Photo by Peter Hove Olesen)

A girl warms up before her performance at a school that is always on the program of travel companies authorized to book tours to the DPRK. We don’t know if the schools we visit represent average North Korean schools. You can find YouTube videos where tourists watch the students play music in this same room. (Photo by Peter Hove Olesen)

Apparently the children in the Kyongsang elite kindergarten play freely. But when we stay in the room for a little longer than the guides stipulate, we cannot help but notice that the children play small roles. They make the same movements, over and over. (Photo by Peter Hove Olesen)

North Korean soldiers guard the truce village of Panmunjom at the Demilitarized Zone (DMZ) which separates the two Koreas on Monday, February 22, 2016, in Panmunjom, North Korea. Though the world's most fortified border can often seem like a tourist trap, drawing throngs of camera-happy visitors on both sides every year, to the military-trained eye the Cold War style standoff along the DMZ is an incident waiting to happen. And with tensions between Seoul, Pyongyang and Washington, this is one of those times when that's more true than ever. (Photo by Wong Maye-E/AP Photo)

North Korean children rest at the side of a road on Monday, February 22, 2016, in Kaesong, North Korea. In response to the North's recent long-range rocket launch, Seoul shut down a factory park in Kaesong jointly run by both Koreas and this has cost the impoverished North a rare source of legitimate hard currency. (Photo by Wong Maye-E/AP Photo)

North Korean children play at the side of a road on Monday, February 22, 2016, in Kaesong, North Korea. (Photo by Wong Maye-E/AP Photo)

North Koreans ride their bicycles on Monday, February 22, 2016, in Kaesong, North Korea. (Photo by Wong Maye-E/AP Photo)

North Koreans cycle past a planetarium at the Three Revolutions Exhibition Hall on Tuesday, February 23, 2016, in Pyongyang, North Korea. (Photo by Wong Maye-E/AP Photo)

North Korean children play at a park on Sunday, February 14, 2016, in Pyongyang, North Korea. (Photo by Wong Maye-E/AP Photo)

North Korean soldiers ride in a truck carrying firewood on Saturday, February 20, 2016, in Wonsan, North Korea. (Photo by Wong Maye-E/AP Photo)

In this Friday, February 19, 2016, photo, North Korean women carry firewood as they walk along a highway in Sinpyong county in North Hwanghae province, North Korea. People cycling, walking while pulling carts or balancing their belongings on their heads along long stretches of the main highways is a common scene on the outskirts of the North Korean capital. (Photo by Wong Maye-E/AP Photo)

North Korean military soldiers gather at Munsu Hill to offer flowers in front of bronze statues of late leaders Kim Il Sung, left, and Kim Jong Il, right, as part of celebrations a day before the birthday anniversary, or “Day of the Shining Star”, of Kim Jong Il on Monday, February 15, 2016, in Pyongyang, North Korea. (Photo by Wong Maye-E/AP Photo)

Military soldiers set up their cameras to photograph a flower display with the portrait of late North Korean leader Kim Jong Il as part of celebrations a day before the birthday anniversary, also known as the “Day of the Shining Star”, of late North Korean leader Kim Jong Il on Monday, February 15, 2016, in Pyongyang, North Korea. (Photo by Wong Maye-E/AP Photo)

North Korean men and women participate in a mass dance party at the Pyongyang Indoor Stadium where the portraits of late leaders Kim Il Sung, left, and Kim Jong Il, right, hang at the entrance as part of celebrations of the “Day of the Shining Star” or birthday anniversary of Kim Jong Il on Tuesday, February 16, 2016, in Pyongyang, North Korea. (Photo by Wong Maye-E/AP Photo)

In this Sunday, February 14, 2016 photo, North Korean men put up a propaganda poster urging its citizens to carry out their country's ruling party's goals for North Korea with an unwavering spirit in Pyongyang, North Korea. North Korea launched a rocket on February 7, carrying what it said was an Earth observation satellite into space. The launch, which came about a month after the country's fourth nuclear test, was quickly condemned by outsiders as a test of banned ballistic missile technology. (Photo by Wong Maye-E/AP Photo)